1. Filed of Invention
The present invention relates to a power converter, and more particularly, the present invention relates to a sampling circuit of the power converter.
2. Description of Related Art
The reflected voltage is utilized to generate a feedback signal for regulating an output of the power converter. The feedback signal is correlated to the output of the power converter. Many prior arts had been disclosed for the detection of the reflected voltage of the transformer, such as “Multiple-sampling circuit for measuring reflected voltage and discharge time of a transformer” U.S. Pat. No. 7,151,681; “Causal sampling circuit for measuring reflected voltage and demagnetizing time of transformer” U.S. Pat. No. 7,349,229; and “Linear-predict sampling for measuring demagnetized voltage of transformer” U.S. Pat. No. 7,486,528. However, the complexity is the drawback of the U.S. Pat. No. 7,151,681. The disadvantage of the U.S. Pat. No. 7,349,229 is the imprecise sampling in response to the dynamic loading or the input-voltage change. The approach of the U.S. Pat. No. 7,486,528 is limited by the turn ratio of the transformer design. The present invention provides a simple and precise method to sample the reflected voltage of the transformer for the power converter operated in DCM (discontinuous current mode) and CCM (continuous current mode).